I was at a customer site installing a server and happened across one of the super cheap 4 gang extension sockets which had previously had a storage heater plugged into it. the casing round the live & neutral pins had melted away on 2 of the sockets and a nearby storage heater had evidence of scorching to the pins.

I wasn't there to test the site but thought i should at least do the responsible thing of notify the office manager and strongly advise them not to use it to which they responded "Yeah I know"

I got sent on a call out to look at a pc that was having intermittent power issues, when i arrived it seemed fine so I took it back to the workshop to try and replicate the fault after 3 days and no faults found i took it back to the office plugged it in & of course no power. I traced the cable back to a surge protector where the cable was haging out the end of the bar with a goof 10-15mm of the 3 cores visable, I unplugged it and found that it had been PAT tested (and passed) less than 2 weeks before. I got another lead plugged it back into the wall socket to find that the socket moved and started buzzing/cracking.

And finally

I bought a 2 Gang extension cable for my tumble dryer. I took it home plugged it in the dryer powered up for a split second then went off. I unplugged the Dryer and got a small jolt from the plug. I tried the dryer in another extension and it worked so i turned my attention to the 2Gang. connecting the socket tester i found that one of the sockets was missing the earth & the other showed L/N reversed

I dug out the receipt and headed off to take it back. I went and grabbed another cable from the shelf and joined the queue, upon reaching the counter and asking to swap one for the other (even though they are the same) and without asking why the somewhat abrasive woman behind the counter simply snapped at me that I cant return it without the packaging.

"OK WELL! this one has just electrocuted me, ive tested it with a socket tester its missing the earth wire and the live/neutral wires are somehow reversed in one socket but not the other, this is potentially lethal & also doesnt work"